Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Virulence profiling”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMedDate not supplied

Biological and molecular characterization of Newcastle disease virus isolates from surveillance of live bird markets in the northeastern United States.

Newcastle disease virus (NDV) is frequently recovered from surveillance samples collected by U.S. Department of Agriculture, Animal and Plant Health Inspection Service personnel in live bird markets. Six NDV isolates, five from chickens and one from a pheasant, were characterized for comparison with reference NDV isolates from poultry and other birds. All isolates tested were of low virulence for chickens. Four of the six isolates were similar to reference lentogens B1 and La Sota, but two isolates, one from a chicken and one from a pheasant, were different. The aberrant chicken isolate had a monoclonal antibody-binding profile like an unusual Canadian pigeon isolate. Sequence analysis of the matrix gene of this isolate demonstrated that it differed from all isolates included in the comparison and therefore may represent a third phylogenetic NDV group. The pheasant isolate had a monoclonal antibody-binding profile typical of other U.S. NDV lentogens but had a matrix gene sequence and hemagglutinin thermostability similar to strains Ulster and Queensland V4 (QV4), viruses originally isolated in Northern Ireland and Australia, respectively. The pheasant virus is the first lentogen isolated in the United States known to be closely related phylogenetically to Ulster and QV4. The unusual chicken and pheasant isolates were readily shed from the intestinal tract during chicken passage, whereas the other isolates were shed from the respiratory tract with little or no intestinal shedding. The frequency in live bird markets of viruses similar to those previously thought to be exotic to the United States in unknown.

Animals↗
PubMed2006

In vivo gene expression analysis identifies genes required for enhanced colonization of the mouse urinary tract by uropathogenic Escherichia coli strain CFT073 dsdA.

Deletional inactivation of the gene encoding d-serine deaminase, dsdA, in uropathogenic Escherichia coli strain CFT073 results in a hypermotile strain with a hypercolonization phenotype in the bladder and kidneys of mice in a model of urinary tract infection (UTI). The in vivo gene expression profiles of CFT073 and CFT073 dsdA were compared by isolating RNA directly from the urine of mice challenged with each strain individually. Hybridization of cDNAs derived from these samples to CFT073-specific microarrays allowed identification of genes that were up- or down-regulated in the dsdA deletion strain during UTI. Up-regulated genes included the known d-serine-responsive gene dsdX, suggesting in vivo intracellular accumulation of d-serine by CFT073 dsdA. Genes encoding F1C fimbriae, both copies of P fimbriae, hemolysin, OmpF, a dipeptide transporter DppA, a heat shock chaperone IbpB, and clusters of open reading frames with unknown functions were also up-regulated. To determine the role of these genes as well as motility in the hypercolonization phenotype, mutants were constructed in the CFT073 dsdA background and tested in competition against the wild type in the murine model of UTI. Strains with deletions of one or both of the two P fimbrial operons, hlyA, fliC, ibpB, c0468, locus c3566 to c3568, or c2485 to c2490 colonized mouse bladders and kidneys at levels indistinguishable from wild type. CFT073 dsdA c2398 and CFT073 dsdA focA maintained a hypercolonization phenotype. A CFT073 dsdA dppA mutant was attenuated 10- to 50-fold in its colonization ability compared to CFT073. Our results support a role for d-serine catabolism and signaling in global virulence gene regulation of uropathogenic E. coli.

Animals↗
PubMed1990

Characterization of an attenuated strain of Actinobacillus pleuropneumoniae, serotype 1.

Pleuropneumonia is an important disease of swine caused by Actinobacillus pleuropneumoniae. Putative virulence determinants include capsule, lipopolysaccharide, and cytotoxin. We studied the virulence and virulence determinants of 2 strains: CM5 and CM5A of serotype 1. Strain CM5 was isolated from a pig with pleuropneumonia and passaged once in vitro; strain CM5A was a substrain of CM5 passaged 70 times in vitro. Pigs challenge exposed to an aerosol of 1.3 x 10(7) colony-forming units of CM5/ml died within 30 hours; pigs challenge exposed to an aerosol of 1.6 x 10(8) colony-forming units of CM5A/ml survived. The average thickness of the capsular layer was 137 nm in strain CM5 and 53 nm in strain CM5A in bacteria treated with homologous antibody and examined by transmission electron microscopy. Similarly, capsular material binding polycationic ferritin was found in colonies of strain CM5, but not in strain CM5A. The ratio of hexosamine to protein in extracted capsule of CM5 was more than twice that of CM5A. The polyacrylamide gel electrophoretic profile of the lipopolysaccharide, outer membrane proteins, and whole cell proteins did not differ between the 2 strains. Also, the amount of cytotoxin or endotoxin produced by the 2 strains during the logarithmic growth phase was not different. The electrophoretic profile of restriction endonuclease digested DNA was similar, with the exception of bands in the 750- and 620-basepair regions. It was concluded that attenuation of strain CM5A during in vitro passage was a result of reduced capsule production and that encapsulation is an important virulence determinant of A pleuropneumoniae, serotype 1.

Actinobacillus↗
PubMed2005

Analysis of differentially expressed transcripts of fungal elicitor- and wound-treated wild rice (Oryza grandiglumis).

Suppression subtractive hybridization was used to construct a subtracted library (ogfw) from plants of a wild rice species, Oryza grandiglumis, subjected to a fungal elicitor and physical wounding. To screen the differentially expressed transcripts in the library, we applied a reverse Northern blot analysis to a cDNA microarray containing 1,152 random clones. Based on the average expression ratio, we selected 156 clones showing an elevated expression level. The elevated expression levels and overall expression profiles over time were verified by Northern blot analysis. A comparative functional categorization of the subtracted expressed sequence tags (ESTs) of the ogfw library against ESTs isolated from blast-infected O. sativa showed that the functional categories of cell rescue, defense and virulence, transcription, and cellular transport and transport mechanism of the ogfw library were threefold higher in the former than in the latter. These subtracted ESTs can be presumed to be related to the defense/resistance system and will be used to investigate the defense mechanisms of wild rice and to provide new insights into the genome of wild rice, which in turn will assist molecular breeding strategies of cultivated rice.

Amino Acid Sequence↗
PubMed1992

Clinical and laboratory profile of AIDS in India.

The clinical features and results of laboratory investigations of the first 19 Indian patients with AIDS seen in our hospital are presented. Weight loss, fever, and diarrhea were the most common symptoms. Tuberculosis (TB) was the most common secondary infectious disease; among 13 patients, seven had only pulmonary TB, five had pulmonary and extrapulmonary TB, and one had only extrapulmonary TB. Oropharyngeal candidiasis was found in 11 patients. Other secondary infections were predominantly by virulent bacteria. Opportunistic infections other than candidiasis were infrequent; one patient had cryptococcosis, two had symptomatic cryptosporidiosis, one had noncoagulase-positive staphylococcus septicemia, and one had cytomegalovirus retinitis. Reduced lymphocyte counts (particularly of the CD4 subset), anemia, hypoalbuminemia, hyperglobulinemia, and elevated liver enzyme levels were frequent laboratory findings. Six patients are under follow-up, two are lost to follow-up, and 11 have died. Lymphocyte counts less than 500/mm3 were only seen in those patients who subsequently died. Response to antituberculosis therapy was good in several patients. Thus, the clinical profile of Indian patients with AIDS is not different from the common picture of patients of low socioeconomic and poor hygienic standards; patients presented with TB, undernutrition, and multiple infections. Therefore, a large population of patients with AIDS in India will not be recognized unless they are tested for evidence of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Virulence gene identification by differential fluorescence induction analysis of Staphylococcus aureus gene expression during infection-simulating culture.

We have employed a strategy utilizing differential fluorescence induction (DFI) in an effort to identify Staphylococcus aureus genes whose products can be targeted for antimicrobial drug development. DFI allows identification of promoters preferentially active under given growth conditions on the basis of their ability to drive expression of a promoterless green fluorescent protein gene (gfp). A plasmid-based promoter trap library was constructed of 200- to 1,000-bp fragments of S. aureus genomic DNA fused to gfp, and clones with active promoters were isolated under seven different in vitro growth conditions simulating infection. Six thousand two hundred sixty-seven clones with active promoters were screened to identify those that exhibited differential promoter activity. Bioinformatic analysis allowed the identification of 42 unique operons, containing a total of 61 genes, immediately downstream of the differentially active putative promoters. Replacement mutations were generated for most of these operons, and the abilities of the resulting mutants to cause infection were assessed in two different murine infection models. Approximately 40% of the mutants were attenuated in at least one infection model.

Abscess↗
PubMed2005

Transcriptional adaptation of Shigella flexneri during infection of macrophages and epithelial cells: insights into the strategies of a cytosolic bacterial pathogen.

Shigella flexneri, the etiologic agent of bacillary dysentery, invades epithelial cells as well as macrophages and dendritic cells and escapes into the cytosol soon after invasion. Dissection of the global gene expression profile of the bacterium in its intracellular niche is essential to fully understand the biology of Shigella infection. We have determined the complete gene expression profiles for S. flexneri infecting human epithelial HeLa cells and human macrophage-like U937 cells. Approximately one quarter of the S. flexneri genes showed significant transcriptional adaptation during infection; 929 and 1,060 genes were up- or down-regulated within HeLa cells and U937 cells, respectively. The key S. flexneri virulence genes, ipa-mxi-spa and icsA, were drastically down-regulated during intracellular growth. This theme seems to be common in bacterial infection, because the Ipa-Mxi-Spa-like type III secretion systems were also down-regulated during mammalian cell infection by Salmonella enterica serovar Typhimurium and Escherichia coli O157. The bacteria experienced restricted levels of iron, magnesium, and phosphate in both host cell types, as shown by up-regulation of the sitABCD system, the mgtA gene, and genes of the phoBR regulon. Interestingly, ydeO and other acid-induced genes were up-regulated only in U937 cells and not in HeLa cells, suggesting that the cytosol of U937 cells is acidic. Comparison with the gene expression of intracellular Salmonella serovar Typhimurium, which resides within the Salmonella-containing vacuole, indicated that S. flexneri is exposed to oxidative stress in U937 cells. This work will facilitate functional studies of hundreds of novel intracellularly regulated genes that may be important for the survival and growth strategies of Shigella in the human host.

Adaptation, Physiological↗
PubMed2026

Metagenomic insights into biogeochemical functional potential and resistome dynamics of PM2.5 microbial communities.

Atmospheric particulate matter harbors diverse microorganisms, yet their functional potential in biogeochemical cycling and the associated risks of resistome remain poorly understood. Here, we performed metagenomic sequencing on PM2.5 samples collected across four months to unravel the microbial genetic repertoire involved in methane, nitrogen, phosphorus, and sulfur cycling, as well as the resistome, and pathogen composition. A broad range of functional genes was detected for each biogeochemical cycle, with more than 65% of gene subtypes shared across all months, indicating conserved functional signatures. In contrast, more than 80% of the resistome showed temporal variation in abundance, with the lowest richness observed in March. Temporal shifts were also observed in resistome composition, with several resistance determinants reaching higher abundances in April and May. Network analysis indicated frequent co-occurrence among several pathogenic and opportunistic taxa. Contig-based profiling identified 51 potential pathogenic taxa, including 32 human- or animal-associated taxa. In addition, both PM10 and PM2.5 concentrations were associated with pathogen abundance and functional gene richness (e.g., antibiotic resistance genes and virulence factors). Together, this metagenomic survey suggests contrasting temporal patterns between conserved biogeochemical functional potential and more variable resistome-related traits in PM2.5 microbial communities. While constrained by limited temporal coverage and sample size, this study provides preliminary insights into the ecological and potential public health relevance of airborne microbial communities in urban environments.

Particulate Matter↗
PubMed1988

Oral immunization with live, avirulent fla+ strains of Salmonella protects mice against subsequent oral challenge with Salmonella typhimurium.

Some strains of Salmonella, when fed to mice, establish a nonlethal, limited infection in the Peyer's patches of the small intestine. When such mice are later challenged orally with a normally lethal dose of virulent Salmonella typhimurium, a protective effect of the prior vaccination is seen. In an effort to characterize the determinant(s) of the avirulent strains responsible for this protective effect, we examined the cell envelope protein profiles of five such protective strains and of eight strains of Salmonella that were both nonpersistent and nonprotective when fed to mice. The protective strains produced high levels of flagellin. We made otherwise isogenic fla+ and fla- derivatives of two such strains and showed that although the fla- derivatives colonized mice as well as did the fla+ strains, the fla- derivatives given orally showed a much reduced ability to protect mice from S. typhimurium challenge. Both fla+ and fla- strains induced cellular immunity in vaccinated mice.

Administration, Oral↗
PubMed2002

Comparative proteomics of Staphylococcus aureus and the response of methicillin-resistant and methicillin-sensitive strains to Triton X-100.

Proteomics is a powerful tool for analysing differences in gene expression between bacterial strains with alternate phenotypes. Staphylococcus aureus strains are grouped on the basis of their sensitivity to methicillin. Two-dimensional gel electrophoresis was combined with MS to compare the protein profiles of S. aureus strains COL (methicillin-resistant) and 8325 (methicillin-sensitive). Reference mapping via this approach identified 377 proteins that corresponded to 266 distinct ORFs. Amongst these identified proteins were 14 potential virulence factors. The production of 41 'hypothetical' proteins was confirmed, and eight of these appeared to be unique to S. aureus. Strain COL displayed 12 protein spots, which included alkaline-shock protein 23 (Asp23) and cold-shock proteins CspABC, which either were not present in strain 8325 or were present at a significantly lower intensity in this strain. Comparative maps were used to characterize the S. aureus response to treatment with Triton X-100 (TX-100), a detergent that has been shown to reduce methicillin resistance independently of an interaction with the mecA-encoded penicillin-binding protein 2a. In response to growth of the bacteria in the presence of TX-100, 44 protein spots showed altered levels of abundance, and 11 of these spots were found only in COL. The products of genes regulated by sigma(B) (the alternative sigma factor), including Asp23 and three proteins of unknown function, and SarA (a regulator of virulence genes) were shown to be present at significantly altered levels. SarA production was induced in TX-100-treated cultures. A protein of the sigma(B) operon, RsbV, was only detected in COL and its production was down-regulated in COL when the strain was treated with TX-100, whereas RsbW was present at reduced levels in both strains. Upon growth of both strains in the presence of TX-100, no effects on the production of the essential methicillin-resistance factor FemA were detected, whereas phosphoglucosamine mutase (GlmM) production was reduced in COL alone. This study suggests that proteins of the sigma(B) and sarA regulons, as well as other factors, are involved in methicillin resistance in S. aureus.

Bacterial Proteins↗
PubMed2005

Effects of long-term storage on plasmid stability in Bacillus anthracis.

The plasmid profiles of 619 cultures of Bacillus anthracis which had been isolated and stored between 1954 and 1989 were analyzed using the Laboratory Response Network real-time PCR assay targeting a chromosomal marker and both virulence plasmids (pXO1 and pXO2). The cultures were stored at ambient temperature on tryptic soy agar slants overlaid with mineral oil. When data were stratified by decade, there was a decreasing linear trend in the proportion of strains containing both plasmids with increased storage time (P < 0.001). There was no significant difference in the proportion of strains containing only pXO1 or strains containing only pXO2 (P = 0.25), but there was a statistical interdependence between the two plasmids (P = 0.004). Loss of viability of B. anthracis cultures stored on agar slants is also discussed.

Bacillus anthracis↗
PubMed2002

High expression of a C protein beta antigen gene among invasive strains from certain clonally related groups of type Ia and Ib group B streptococci.

Serotyped strains of group B streptococci can be divided into subtypes based on restriction endonuclease digestion patterns (RDP). Profiles of cell-bound proteins were compared among RDP types. Proteins that showed a remarkable difference in the degree of expression were found among strains of RDP Ia-3, which has been considered potentially virulent, as well as of RDP Ib-1. For RDP Ia-3 strains, the protein was predominant in strains from cerebrospinal fluid (CSF) but was mostly a minor component in other strains. For RDP Ib-1 strains, the protein was predominant in strains from CSF, showed diversity in strains from blood, and was mostly a minor component in other strains. By N-terminal sequencing analysis, the protein was identified as a C protein beta antigen. The level of bound immunoglobulin A (IgA) or anti-beta antigen monoclonal antibody correlated with the level of expressed beta antigen, and invasive strains showed remarkably high levels of binding; the exception was a CSF-derived strain of RDP Ib-1 which produced a large amount of beta antigen and showed a high level of binding of anti-beta antigen monoclonal antibody but no IgA binding. PCR-based amplification revealed that the beta antigen gene was detected in all RDP Ia-3 and Ib-1 strains but was not found in any strains of other RDP types. Competitive reverse transcriptase PCR demonstrated that the difference in the amount of protein produced was due to the difference in the level of expression of the beta antigen mRNA. Our findings imply that differences in gene expression for a protein may contribute to the invasiveness of RDP Ia-3 and Ib-1 strains for the host.

Antibodies, Bacterial↗
PubMed2005

Sequence diversity and antigenic variation at the rag locus of Porphyromonas gingivalis.

The rag locus of Porphyromonas gingivalis W50 encodes RagA, a predicted tonB-dependent receptor protein, and RagB, a lipoprotein that constitutes an immunodominant outer membrane antigen. The low G+C content of the locus, an association with mobility elements, and an apparent restricted distribution in the species suggested that the locus had arisen by horizontal gene transfer. In the present study, we have demonstrated that there are four divergent alleles of the rag locus. The original rag allele found in W50 was renamed rag-1, while three novel alleles, rag-2 to rag-4, were found in isolates lacking rag-1. The three novel alleles encoded variants of RagA with 63 to 71% amino acid identity to RagA1 and each other and variants of RagB with 43 to 56% amino acid identity. The RagA/B proteins have homology to numerous Bacteroides proteins, including SusC/D, implicated in polysaccharide uptake. Monoclonal and polyclonal antibodies raised against RagB1 of P. gingivalis W50 did not cross-react with proteins from isolates carrying different alleles. In a laboratory collection of 168 isolates, 26% carried rag-1, 36% carried rag-2, 25% carried rag-3, and 14% carried rag-4 (including the type strain, ATCC 33277). Restriction profiles of the locus in different isolates demonstrated polymorphism within each allele, some of which is accounted for by the presence or absence of insertion sequence elements. By reference to a previously published study on virulence in a mouse model (M. L. Laine and A. J. van Winkelhoff, Oral Microbiol. Immunol. 13:322-325, 1998), isolates that caused serious disease in mice were significantly more likely to carry rag-1 than other rag alleles.

Alleles↗
PubMed2006

Salmonella enterica highly expressed genes are disease specific.

During in vitro broth culture, bacterial gene expression is typically dominated by highly expressed factors involved in protein biosynthesis, maturation, and folding, but it is unclear if this also applies to conditions in natural environments. Here, we used a promoter trap strategy with an unstable green fluorescent protein reporter that can be detected in infected mouse tissues to identify 21 Salmonella enterica promoters with high levels of activity in a mouse enteritis model. We then measured the activities of these and 31 previously identified Salmonella promoters in both the enteritis and a murine typhoid fever model. Surprisingly, the data reveal that instead of protein biosynthesis genes, disease-specific genes such as Salmonella pathogenicity island 1 (SPI-1)-associated genes and genes involved in anaerobic respiration (enteritis) or SPI-2-associated genes and genes of the PhoP regulon (typhoid fever), respectively, dominate Salmonella in vivo gene expression. The overall functional profile of highly expressed genes suggests a marked shift in major transcriptional activities to nutrient utilization during enteritis or to fighting against the host during typhoid fever. The large proportion of known and novel essential virulence factors among the identified genes suggests that high expression levels during infection may correlate with functional relevance.

Animals↗
PubMedDate not supplied

Giardia duodenalis: inter-strain variability of proteins, antigens, proteases, isoenzymes and nucleic acids.

Giardia duodenalis isolates from asymptomatic or symptomatic patients and from animals present similarities and differences in the protein composition, antigenic profile, pattern of proteases and isoenzymes, as well as in nucleic acids analysis. In the present overview, these differences and similarities are reviewed with emphasis in the host-parasite interplay and possible mechanisms of virulence of the protozoon.

Animals↗
PubMed2002

Technological performance of several Lactococcus and Enterococcus strains of dairy origin in milk.

Thirty-nine strains (29 Lactococcus strains and 10 Enterococcus strains) isolated from five different artisanal cheeses were subjected to technological characterization. Several strains of lactococci and enterococci produced lactic acid at a rate and final concentration suitable for large-scale cheesemaking. However, extensive phenotypic differences between strains were encountered. Proteolytic activity correlated quite well with acidification for all strains, with the more proteolytic strains being the best acidifiers. The strains were also assayed for the production of organic acids and volatile components in milk. With few exceptions, enterococcus isolates produced more formic acid and acetic acid than did lactococcus isolates. The volatile-compound profiles obtained were rather simple. The main volatile component produced by most strains was ethanol. Since the inclusion of enterococcus strains in food systems is controversial, tests were also performed to detect recognized determinants of virulence (namely, aggregation, gelatinase and hemolysin production, and antibiotic resistance). Aggregation in both liquid and solid media was observed only for two Enterococcus durans isolates. None of the strains studied produced gelatinase under the conditions of the assay. Beta-hemolysin activity was clearly detected in two Enterococcus faecalis strains, which also produced the biogenic amine tyramine from tyrosine in a laboratory medium. In general, the enterococcus strains were more resistant to the antibiotics assayed than were the lactococcus strains. Both the minimum inhibitory concentration (MIC) modes and the highest MIC values were consistently higher for the enterococci. Nevertheless, particular strains of lactococci were resistant to antibiotics such as bacitracin, cephalothin, clindamycin, streptomycin, and tetracycline.

Animals↗
PubMed2000

Epidemiology and characterization of animal Salmonella enterica subspecies Enterica serotype typhimurium DT104 in Hungary.

Reports on the internationally emerging significance of multiresistant zoonotic Salmonella in animals and man prompted studies to estimate the significance of multiresistant Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) phage type DT104 of animal origin in Hungary. A collection of 231 strains (primarily of goose, turkey, poultry and porcine origin from the years 1997-1998) was tested for resistance against 7 selected antibiotics (ampicillin, chloramphenicol, enrofloxacin, nalidixic acid, streptomycin, tetracycline and sulphamethoxazole). Strains with resistance against 3 or more were defined as multiresistant. All strains were phage typed using Felix-Callow's S. Typhimurium phage typing system, and 91 of them (suspect DT104) were also typed according to Anderson's definitive typing (DT) system. In this study, 14% of animal strains from 1997-1998 was classified as DT104, for which turkey, pig and duck seemed to be the main carriers, and the multiresistant non-DT104 strains represented a further 6% of this collection. The prevalence of DT104 was highest among strains of turkey origin (50%), followed by strains of pig (29%), chicken (25%), duck (19%), and goose (3%) origin. The other DT104 related phage types (DT12 and U302) were only detected in the case of 4 strains (2 of porcine, and one each of turkey and of goose origin). The DT104 corresponded to the Felix-Callow types 2/3 or 2c/3 in each case, except in the case of 3 turkey strains where they corresponded to type 35/3. Nalidixic acid resistance was detected in all multiresistant turkey strains and in some of other animal origin but none of these strains were resistant to enrofloxacin. A retrospective analysis (based on the above relationship) indicated that S. Typhimurium strains corresponding to DT104 could be present and increase in the Hungarian farm animal population from about 2% to 20% between 1985 and 1990, in a manner similar to the emergence of human DT104, as reported elsewhere (Pászti et al., 2000). The 91 suspect DT104 strains were also tested for plasmid profile and for spvC gene indicating the presence of the large serotype specific plasmid (Ssp). No characteristic plasmid profile could be attributed to S. Typhimurium DT104. The serovar-specific large plasmid was detected by PCR for spvC in 100% of DT104 strains and in 77% of the non-DT104 strains. The virulence of two DT104 strains was tested in orally infected day-old chicks and compared with virulence of 4 non-DT104 strains. Higher colonizing virulence of DT104 strains could be established as compared to the other strains.

Animals↗
PubMedDate not supplied

Comparison of Pasteurella multocida serotype 3,4 isolates from turkeys with fowl cholera.

Nine isolates of Pasteurella multocida serotype 3,4 were isolated from turkeys that had been vaccinated against fowl cholera but that subsequently experienced outbreaks of fowl cholera. These isolates were compared with the CU vaccine strain. Characteristics examined were antimicrobial susceptibility profiles; carbohydrate fermentation; production of bacteriocin, siderophore, and hemolysin; resistance to serum complement; membrane proteins; enzyme activities; presence of plasmids; transferability of R-plasmids; and pathogenicity. Differences were observed between the CU strain and virulent isolates of P. multocida serotype 3,4 for resistance to serum complement, presence of plasmids, hemolysis, membrane proteins, and pathogenicity. Other parameters compared did not differ significantly between the two groups. The presence of plasmids and resistance to the lytic action of complement of the isolates of P. multocida serotype 3,4 correlated with the mortality rates caused by these bacteria.

Animals↗